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Furnace Heat Flux Probes

Product Details

Convertible to Measure both Total Flux and Radiant Flux 

Our Furnace Heat Flux Probe, Model GTW-xx-20221, is a water cooled probe with a diameter of one inch and length of four feet, containing a Schmidt-Boelter Heat Flux Sensor and is used for insertion into an industrial furnace for the direct measurement of heat flux.  The probe produces a self-generated millivolt signal which is directly proportional to the heat flux component under measurement.  The probe can be used for measuring total heat flux (convective plus radiated) or with a minor adjustment by the user can be used to measure only radiated flux. The heat flux probe is calibrated traceable to NIST standards and has a calibration accuracy of ±3%.  Probes up to 48” long are shipped in a foam lined carrying/storage case suitable for shipping or travel to site. 

The probe is typically placed through a furnace test or observation port in an environment of up to 1600 °C and the self-generated EMF is read directly on the H-201 Heat Flux Indicator or another millivolt readout device.  Each probe is designed to produce a linear output from 0 to nominally 10 mv over the heat flux range specified by the user. 

The probe can be used to measure total heat flux (convective plus radiated) or the calcium fluoride window attachment can be field installed for blocking convective flux when it is desired to measure only the radiated flux.  With the window installed, an inert gas is usually supplied to the purge port which supplies a radial flow across the window keeping it clean of soot.  The window can be removed, as in the mode for measuring total flux, and by supplying a purge flow will eliminate the convective flux for a radiated flux measurement.  This mode has the advantage of measuring the total and radiated flux alternately by turning the purge on and off without removing the probe from the furnace.  When used in this manner, a small tare correction factor is used with the radiant flux data. 

Total Heat Flux Measurement 

Convertible to windowed radiometer 

Convertible while inside the furnace to a windowless radiometer 

More than 150° field of view 

1 inch diameter probe 

Water cooled, nitrogen purged 

Sturdy construction 

Linear and high output 

Calibration included 

48 inch standard length 

Foam lined hard-side case included 


Furnace and flame total heat flux and radiation heat flux measurements 

Radiant flux measurement with or without window 


Ranges Available: from 0 – 2 Btu/ft2sec to 

0 – 50 Btu/ft2sec 

Output Signal: 10 mv nominal at full range, calibrated 

Maximum Non-Linearity: ±2% of full range 

Repeatability: ±1/2% 

Calibration Accuracy: ±3% 

Probe Diameter: One inch 

Probe Length: 48 inches 

Cooling Water Requirements: 3 GPM @ 60 psig, 120°F supply recommended to minimize condensate 

Purge Requirements: 1.0 CFM (125 psig max) inert gas 

Window: Calcium fluoride window std., zinc selenide and zinc sulfide available 

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